Apparatus for measuring the viscosity of liquids are well known, for example, such apparatus is shown and described in German Patent Nos. DT-OS 1015625 and DT-OS 2204878 and also in U.S. Pat. No. 4,388,823. These patents provide for obtaining measurements by elevating a metallic ball in a tube filled with a liquid, the viscosity of which is to be measured by means of a permanent magnet or electromagnet, allowing the ball to fall and measuring the lapse of time that it takes the ball to fall through a predetermined distance. The equipment shown in these patents requires considerable time to set up so that the liquid undergoes change in viscosity with lapse of time or exposure, hence, it is not possible to obtain accurate measurements without the use of anticoagulants or other chemicals. Furthermore, the aforesaid devices are not only inappropriate, but require relatively large quantities of liquid and, in particular, if used for measuring the vicosity of blood, require that the blood sample be taken by means of a syringe, which is highly objectionable to many patients. Obtaining samples of blood by pricking the fingertip and drawing the sample by means of a capillary provides such a small quantity of blood as not to be sufficient for use with the aforesaid equipment.
It is an object of this invention to provide a viscosimeter which can be easily manipulated, prepared for use quickly without substantial lapse of time, thus to minimize any appreciable change in viscosity from the time of taking the sample to the time of measuring the viscosity without the need for adding anticoagulants or other chemicals so that unprepared blood may be measured which enables obtaining accurate and repeatable results, requires no greater volume of blood than can be conveniently obtaining by pricking the fingertip and drawing the sample by means of a capillary which enables selecting the measuring cycle according to the viscosity of the liquid and provides for using expendable, low-cost capillaries. Further objects are to provide a microviscosimeter of the kind wherein a capillary tube is used to take samples of the fluid, the viscosity of which is to be measured, provided with a metal ball arranged to free fall within the tube when the latter is supported at an angle and a holder therefor for supporting the capillary tube at a selected angle for fluids of different viscosity, which can be heated to maintain the capillary tube at a constant temperature during measuring, and which is provided with a window which enables observing the condition of the fluid and the descent of the ball during the measuring operation. Other objects are to provide, in combination with the holder, a preheater for preheating a series of capillary tubes to the temperature of the holder preparatory to taking measurements to thus enable rapid processing of a series of capillaries and to provide two-part capillaries with a precisely fabricated outer part and an inner part less precisely fabricated which when inserted into the outer part takes the configuration of the outer part.